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A theory on why anorexics spurn food

July 22, 2009 | 7:00
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What causes someone to starve himself? That's the central question among researchers hoping to solve the puzzle of anorexia. A new theory, proposed by one of the leading researchers on the disorder, suggests that faulty wiring in the brains of people with anorexia causes them to fail to recognize when they are hungry and feel anxious and depressed when they do eat.

"Individuals with anorexia tend to report that dieting reduces anxiety, while eating increases it," said Dr. Walter H. Kaye, the lead author of the report, in a news release. "This is very different from most individuals, who experience hunger as unpleasant." Kaye is director of the Eating Disorders Program at UCSan Diego.The theory, published online this week in Nature Reviews Neuroscience, helps explain the motivation propelling people with anorexia to starve themselves. In effect, starvation makes them feel better -- psychologically.

Kaye's research suggests that anorexia occurs in people who tend be perfectionists or have anxiety or obsessive-compulsive tendencies. Changes in hormones triggered by puberty may promote these tendencies. Once a patient begins an altered pattern of eating, neuro-chemical changes take place in the brain. Brain scans performed by the co-author of the study, Julie L. Fudge, of the University of Rochester Medical Center, show that people with anorexia have an imbalance between circuits in the brain that regulate reward and emotion and circuits associated with consequences and the ability to plan ahead.

"Brain-imaging studies also show that individuals with anorexia have alterations in those parts of the brain involved with bodily sensations, such as sensing the rewarding aspects of pleasurable foods," said another co-author of the study, Martin Paulus. "Anorexics may literally not recognize when they are hungry."

The science suggests that successful treatment of the disorder may lie in correcting these neural imbalances.